I. Field of the Invention
The present invention relates generally to cartridge filter constructions, and more particularly to a sealable end cap construction for a cartridge filter.
II. Description of the Prior Art
Cartridge filters are typically cylindrical in shape and include an end cap formed around each axial end of the cartridge filter. To date, most cartridge filters are constructed with stamped sheet metal end caps held in place and sealed to the cartridge filter with various potting compounds such as plastisol, urethane or epoxy. An adhesive is then applied to the outer exposed surface of the end cap to attach a gasket to the end cap. This previously known cartridge filter end cap construction is necessarily expensive, not only in materials, but also in labor costs due to the multiple manufacturing operations required to construct the end cap.
In more recent developments the previously known sheet metal end cap is eliminated and, thereinstead, an end cap is cast or molded onto the cartridge filter. If the particular cartridge filter application does not require a high degree of chemical resistance, the end cap may be cast from such materials as plastisols or urethanes so that a gasket is formed as an integral part of the end cap due to the resilience of these materials.
However, when the filter application requires a high degree of chemical resistance, particularly at elevated temperatures, elastomeric materials, such as plastisols and urethanes, begin to break down by shrinking, cracking, dissolving, or the like. Needless to say, any of these results create an unsatisfactory seal between the cartridge filter and the cartridge filter holder. In order to provide a moldable cartridge filter end cap for applications requiring a high degree of chemical resistance, previously known end caps have been cast from a chemically resistant material such as epoxy. However, epoxy materials are generally non-resilient so that a resilient seal must thereafter be gluded to the epoxy end cap in order to provide an adequate seal between the cartridge filter and the cartridge filter holder. Although this previously known cartridge filter end cap construction is less expensive than the sheet metal end cap, the epoxy-adhesive-gasket filter end cap construction is disadvantageous in that additional manufacturing operations and materials are required for its construction.